package cn.zengfansheng.loadpic;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.BitmapFactory.Options;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.view.WindowManager;
import android.widget.ImageView;
public class MainActivity extends Activity {
private ImageView iv;
private WindowManager wm;
private int windowHeight;
private int windowWidth;
@SuppressWarnings("deprecation")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
iv = (ImageView) this.findViewById(R.id.iv);
// TODO 1、获取手机屏幕大小
wm = (WindowManager) this.getSystemService(WINDOW_SERVICE);
// 1-1 高版本获取屏幕大小
// Point outSize = new Point();
// wm.getDefaultDisplay().getSize(outSize);// Call requires API level 13 (current min is 8):android.view.Display#getSize
// 1-2低版本获取屏幕大小
windowWidth = wm.getDefaultDisplay().getWidth();
windowHeight = wm.getDefaultDisplay().getHeight();
}
/**
* 加载一张图片
* @param view
*/
public void loadPic(View view) {
/*
这是不行的，当图片大小超过dalvik虚拟机内存带下，会出现OOM异常
String file = Environment.getExternalStorageDirectory()+"/fireworks.jpg";
System.out.println("file:"+file);
Bitmap bitmap = BitmapFactory.decodeFile(file);
iv.setImageBitmap(bitmap);*/
// 解决方案：
// 1.获取图片的宽高
// 2.获取手机屏幕的宽高
// 3.分别计算水平和竖直方向的缩放比例.
// 4.重新设置真正的解析Bitmap
// TODO 2、获取图片大小
String file = Environment.getExternalStorageDirectory()+"/fireworks.jpg";
Options opts = new Options();
opts.inJustDecodeBounds = true;// 如果为true,不去真正的解析bitmap 只是解析bitmap的头信息.
BitmapFactory.decodeFile(file, opts);//whether the image should be completely decoded, or just is size returned.
// 参数2：null,完全加载图片到内存，否则按比例缩放加载
int outWidth = opts.outWidth;
int outHeight = opts.outHeight;
System.out.println("图片宽：" + outWidth);
System.out.println("图片高：" + outHeight);
System.out.println("屏幕宽：" + windowWidth);
System.out.println("屏幕高" + windowHeight);
// TODO 3、缩放比例
int scale = 1;
int scaleX = outWidth / windowWidth;
int scaleY = outHeight / windowHeight;
if (scaleX > scaleY) {
scale = scaleX;
} else {
scale = scaleY;
}
opts.inSampleSize = scale;// 如果大于1，比如4，那么尺寸为原来的1/4 * 1/4 = 1/16的大小;如果<=1,和原来大小一致。
System.out.println("缩放比例：" + scale);
// TODO 4、重新设置真正的解析Bitmap
opts.inJustDecodeBounds = false;
Bitmap bitmap = BitmapFactory.decodeFile(file, opts);
iv.setImageBitmap(bitmap);
}
}
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